House and Senate negotiators Monday announced an agreement on a giant $662 billion defense authorization bill, including modifications to its detainee language they hope will address White House concerns about that section and avoid a possible veto by President Barack Obama.

In particular, the lawmakers added language to make clear that nothing in the bill requiring military custody of al Qaeda suspects would interfere with the ability of civilian law enforcement to carry out terrorism investigations and interrogations in the United States.

"We felt there was ample assurance in the Senate bill that there would be no interference with civilian interrogations and investigations. We had a number of provisions in the Senate bill to make sure that was not the case," said Sen. Carl Levin, D-Michigan, chairman of the Senate Armed Services Committee.

"However, there were some people who raised concerns that there was interference with FBI or other civilian authorities in terms of their operations. That was not our intent. That was not our language. But we added some significant provisions to reassure everybody that that is not the case.

"We took significant steps to address the administration's concerns in those areas," said Rep. Adam Smith, D-Washington, the top Democrat on the House Armed Services Committee.

"We had numerous meetings with the administration, we had a meeting with the director of the FBI. We feel like we were able to satisfy, we hope, most of their concerns," said Sen. John McCain of Arizona, the top Republican on the Senate Armed Services Committee. "This does not change existing law and this legislation includes a national security waiver if the president chooses to exercise it."

The waiver would allow the president to transfer a suspect from military to civilian custody if he chooses.

The lawmakers also agreed on tough sanctions language for the Iranian Central Bank, aimed at punishing Iran for its nuclear program. The White House had expressed opposition to that provision as well but it received broad support in Congress so lawmakers are hopeful the president will accept the language.

The measure "will put real additional pressure on the Iranians so they are going to pay a bigger and bigger price, if they continue to move towards nuclear weapons," Levin said.

In addition, lawmakers agreed to tough new restrictions on Pakistan to ensure that country is not participating in the manufacture and transport of improvised explosive devices -- those hidden bombs that have caused havoc for coalition forces in Afghanistan.

"We've had some shaky relations with Pakistan lately. We need them, and they need us," said Rep. Buck McKeon, R-California, the chair of the House Armed Services Committee. "We have frozen some of the money that we will be sending to Pakistan until they offer more assurances, more help in this area of ... fertilizer and the things that go into making IEDs," McKeon said.

The House could take up the bill as early as Wednesday and the Senate soon after, the lawmakers said.